CAPE CANAVERAL, Fla., Feb. 4 (UPI) — A Russian Progress rocket brought food, fuel and other critical gear to the International Space Station on Tuesday, as NASA prepared for a memorial service to honor the seven fallen Columbia astronauts.

The unmanned Russian cargo ship docked at the orbital outpost at 9:49 a.m. ET after a two-day journey. The supplies are critical for keeping the space station staffed now that NASA's space shuttles are indefinitely grounded, pending the results of the Columbia investigation.

Columbia was returning to Earth from a 16-day space research mission on Saturday when it perished over Texas. Investigators suspect the shuttle's heat-protective tiles on the left wing were damaged and unable to shield the ship during its high-speed plunge through the atmosphere.

Unlike the Challenger accident 17 years ago, NASA's space shuttles are being used to build and maintain an outpost in orbit. The day of the accident, the station's old cargo ship, which was used to hold the trash, was discarded, but not before station program managers in Houston and Russia thoroughly reviewed plans in light of what is expected to be a lengthy delay before shuttle missions to the station resume.

"We immediately worked with the Russian space agency first to determine if the undocking of (the old cargo ship) would limit any future options needed for station," said program manager Bill Gerstenmaier. "We then focused on reviewing the (new cargo ship's) manifest in detail to determine if its launch should be delayed to allow for addition of different cargo."

NASA and Russian officials cleared the ship for launch and it lifted off from the Baikonur Cosmodrome in Kazakhstan on Sunday.

Station commander Ken Bowersox, science officer Don Pettit and cosmonaut Nikoli Budarin are expected to begin unloading the freight on Wednesday. The crew was scheduled to return to Earth next month, but will stay in orbit for at least an extra two months and possibly longer.

"Whatever happens," said Sen. Bill Nelson, D-Fla., "you can be assured that we are not going to give up our investment in the International Space Station."